Underwater surveying and inspection is a significant component of many marine and oceanographic sciences and industries. Considerable costs are incurred in surveying and inspection of artificial structures such as ship hulls; oil and cable pipelines; and oil rigs including associated submerged platforms and risers. There is great demand to improve the efficiency and effectiveness and reduce the costs of these surveys. The growing development of deep sea oil drilling platforms and the necessity to inspect and maintain them is likely to push the demand for inspection services even further. Optical inspection, either by human observation or human analysis of video or photographic data, is required in order to provide the necessary resolution to determine their health and status.
Conventionally the majority of survey and inspection work would have been the preserve of divers but with the increasing demand to access hazardous environments and the continuing requirement by industry to reduce costs, the use of divers is becoming less common and their place being taken by unmanned underwater devices such as Remotely Operated Vehicles (ROV), Autonomous Underwater Vehicles (AUV) and underwater sentries.
ROVs and AUVs are multipurpose platforms and can provide a means to access more remote and hostile environments. They can remain in position for considerable periods while recording and measuring the characteristics of underwater scenes with higher accuracy and repeatability.
An underwater sentry is not mobile and may be fully autonomous or remotely operated. An autonomous sentry may have local power and data storage while a remote operated unit may have external power.
Both ROVs and AUVs are typically launched from a ship but while the ROV maintain constant contact with the launch vessel through an umbilical tether, the AUV is independent and may move entirely of its own accord through a pre-programmed route sequence.
The ROV tether houses data, control and power cables and can be piloted from its launch vessel to proceed to locations and commence surveying or inspection duties. The ROV relays video data to its operator through the tether to allow navigation of the ROV along a desired path or to a desired target.
Obtaining 3D data of an underwater scene can be an important part of carrying out a survey. Known methods including time of flight measurements and laser line scanning may require expensive or complex technology and may suffer from slow acquisition times and or deployment complications.
It is an object of the present disclosure to overcome at least some of the above-mentioned disadvantages. In particular, it is an objective of the present invention to allow high speed 3D real time point cloud generation at high resolution typical on camera sensors. By high speed, we mean on a moving underwater vehicle.